Wednesday, May 12, 2010

Too Much of a Good Thing?!

By: John Hobbs MEd; Source Endurance Senior Consultant

Free radicals and antioxidants seem to be popular buzz words in the health media. Free radicals, also called reactive oxygen species (ROS), have been associated with several negative processes in the body. They can increase cell death without inflammation that would have normally stimulated adaptations (Hoffman-Goetz & Pedersen 2006) with further end results that can include aging and disease conditions (Murphy 2009). Furthermore, if I told you exercise increases the production of ROS, some people would use this as a great excuse to never go to the gym again or at least have the competitive cyclist wondering what kind of damage they did in last weekend’s three hour race.

Why in the world would anybody want these in their body? Well, they may actually do some good. An entire spectrum of chemical receptors turn processes on and off in your body. Some signal that you should have eaten that energy bar in your pocket as you bonk while others signal to repair damage and cause responses to stress. Restow et al (2009) looked at the effects of the naturally occurring increase in ROS with exercise on some of the health benefits associated with training. And making the research more applicable, the ROS were combated with vitamins C and E, two commonly ingested antioxidants. The results showed that the increased insulin sensitivity associated with exercise was decreased with antioxidant treatment. Additionally, individuals who were trained at the beginning of the study and were part of the treatment group showed decreased insulin sensitivity meaning that by this measurement, they had taken steps back in their exercise related health benefits. The possible implications of this are large. As indicated by Restow, this could have a major effect on diabetes prevention and treatment. Additionally, this is just one health benefit being analyzed. Future work may indicate more of the effects of exercise being undermined.

What if health isn’t your main priority? You just want to go fast and win races. Gomez-Cabrera et al (2008) looked at just that. Their work indicated that using vitamin C as an antioxidant may inhibit the training induced increase in mitochondria in skeletal muscle. Mitochondria are essentially the power plants of the muscle creating usable energy from carbohydrates and fats. More mitochondria means less stress on the body and an increase in lactate threshold. This leads to you to going faster and farther. VO2max also increased with training in untreated groups, but the same response was not seen in the Vitamin C groups. Additionally, your body comes with built in mechanisms to deal with the ROS. The researcher’s findings indicate that the supplements may also hinder these natural mechanisms.

The purpose of this is not to encourage you to throw away your multi-vitamins and avoid fruits and vegetables. However it serves as a bit of education and hopefully discourages you from super-loading on vitamin C after your training rides. Also, it puts a bit of perspective on the processes in the body. Many times, some is good and more is bad. And we tend to focus on the bad and do not stop to think that there may be some underlying benefit. Another example would be histamines. Yes, those guys that are associated with your allergies that cause you watery eyes and other problems. So what good can these things do? They are released in response to a wound as part of an inflammation response (Lewis, Heitkemper, Dirksen, O’Brien, & Bucher 2007). The same group of chemicals that can be annoying enough to have people pop anti-histamines in the morning facilitate the early stages of healing your road rash. In the end, your body has ways of naturally responding to and adapting to stress. The trick with training is learning how maximize these natural adaptations and minimize the negative effects.

Gomez-Cabrera, M., Domenech, E., Rogmanoli, M., Arduini, A., Borras, C., Pallardo, F., et al. (2008). Oral administration of vitamin C decreases muscle mitochondrial biogenesis and hamper training induced adaptations in endurance performance. The American Journal of Clinical Nutrition, 87, 142-149.

Hoffman-Goetz (2006). Exercise and the immune system. ACSM’S Advance Exercise Physiology. Baltimor, MD, Lippincott Williams and Wilkins.

Murphy, M. (2009). How mitochondria produce reactive oxygen species. Biochem Journal, 417, 1-13.

Ristow, M., Zarske, K., Oberbach, K., Kloting, N., Birringer, M., Kiehntopf, M., et al. (2009). Antioxidants prevent health-promoting effects of physical exercise in humans. Proceeding of the National Academy of Sciences of the United States of America, 106, 8665-8670.